If there are more than three participants, and all are within the VCCS, they should be able to use the free VCCS toll-avoidance network to have the call. (Here is the web site with detailed instructions: http://helpnet.utility.vccs.edu/NOC/VoiceIP/ConfInstructions.htm
From NVCC, here are the phone numbers you use to connect to the toll-avoidance network. You dial this number, then dial the number for the conference call you are trying to reach. YOU DO NOT NEED AN IP PHONE FOR THIS! It just uses the VCCS network for the call.
For speed dial use *60 at all campuses.